Expose CompressorType variable for heat pumps

[ekpresent]

The LARGEEE run wants to use ASHP speeds other than the ones that are currently assigned based on SEER in ResStock. Therefore we need the CompressorType variable exposed.

[joseph-robertson]

@ekpresent See https://openstudio-hpxml.readthedocs.io/en/latest/workflow_inputs.html#air-to-air-heat-pump for current capabilities/limitations here. While heat_pump_cooling_compressor_type is an argument we could assign using the lookup, both heat_pump_heating_efficiency (e.g., HSPF) and heat_pump_cooling_efficiency (e.g., SEER) are still required.

Here is the map for defaulting compressor type based on SEER:

if seer <= 15
  return HPXML::HVACCompressorTypeSingleStage
elsif seer <= 21
  return HPXML::HVACCompressorTypeTwoStage
elsif seer > 21
  return HPXML::HVACCompressorTypeVariableSpeed
end

[ekpresent]

@joseph-robertson the heat pumps specced for inclusion in the run include a SEER1 16 single stage and a SEER1 20 variable speed (per the advice of Jon and others), which is why we want the variable exposed. Jeff actually was able to point us to those lines in HVAC.rb that would mean both the SEER1 16 and the SEER1 20 would be modeled as two-stage, and that's not what we want.

[ekpresent]

CompressorType per https://openstudio-hpxml.readthedocs.io/en/latest/workflow_inputs.html#id362

So we would be specifying SEER(1), HSPF(1), capacity retention, and compressor type all independently but reasonably.

[joseph-robertson]

@ekpresent I'm a little confused. Argument heat_pump_cooling_compressor_type is already exposed. It is optional; it is not currently called out in the lookup (and so is defaulted according to the map above), but certainly could be called out in the lookup.

Is this issue about requesting that the lookup be updated to explicitly assign values to heat_pump_cooling_compressor_type? Or even adding new options to the lookup for the "SEER1 16 single stage" and "SEER1 20 variable speed" scenarios you reference above?

[ekpresent]

Wait that's great. As long as we can already use that to override the default we're good to go. Didn't realize that was the case. @whiphi92